Right-hook crashes in right-hand traffic where cyclists going straight are struck by right-turning vehicles pose a major safety concern. This study aims to establish to which extent such conflicts may stem from non-driving-related tasks (NDRT), low saliency of cyclists (covertness), or drivers' insufficient knowledge of applicable rules. Forty-four drivers participated in a fixed-base driving simulator study using an extended reality (XR) setup with integrated eye tracking. Participants were stratified by urban cycling experience (cyclist-drivers vs. drivers) and self-reported driving style (cautious vs. assertive). Each drove an urban route including 12 right-turn-on-yield scenarios, with and without NDRT. Observed visual sampling was combined with a questionnaire-based rule knowledge assessment to examine whether scanning failures were due to workload or lack of rule knowledge. NDRT engagement primarily reduced default glances while glances to relevant areas (Left, Right, Over Shoulder) were preserved. Over-the-shoulder checks were rare overall. In 85 % of right-turns, no such glance occurred before turning, regardless of NDRT status. Rule knowledge mirrored these patterns, with drivers being more likely to correctly indicate the requirement to yield to salient crossing traffic streams of cars (96 % correct) or cyclists and pedestrians (81 % correct) than non-salient crossing bicycle or pedestrian traffic (46 % correct). Drivers with cycling experience scored slightly better overall but still missed nearly half of the non-salient yielding requirements. The findings indicate that gaps in rule knowledge contribute to failures to check for cyclists. Countermeasures should prioritise systemic interventions, complemented by education, rather than solely relying on behaviour-focused measures.

Train drivers’ outside attention impacts the chance of acting in time to avoid potential collisions with people or other objects. This project aimed to study the effect of the in-cabin signalling system ETCS on driver attention. We specifically examined gaze behaviour in events of special relevance for train driving, such as unattended level-crossings, with and without speed changes. An eye-tracking study was conducted in a simulated environment with 40 experienced Swedish train drivers driving the same route equipped with the Swedish lineside signalling system ATC and ETCS, respectively. The results showed that ETCS generally affected drivers’ outside attention negatively. Compared to ATC, with ETCS significantly more glances were directed inside the cabin at the expense of outside glances. When assessing the gaze behaviour at unattended level-crossings with and without speed changes, approximately 20 percent less attention was spent towards the outside when approaching an unattended level-crossing with a speed change. We conclude that ETCS negatively affects outward attention and thus reduces the chances that the driver will detect a person or other object on the track and act in time to avoid a collision. As speed changes negatively affect outward attention, we recommend that speed changes should be avoided in critical parts of the track where the risk of collision is higher. The results should also have implications for the design of connected driver advisory systems, which provides the driver with real-time guidance on speed operation via a tablet or screen and thus, demand driver attention.

Conflicts arise when motor vehicles cross cycle paths during turns, often due to drivers neglecting over-the-shoulder glances. This paper examines the visual attention of car drivers at urban unsignalized intersections, considering turning direction, cross traffic, and cyclist approaching from behind.A study with 44 participants was conducted using a fixed-base driving simulator equipped with an eXtended Reality (XR)-based visual system, which provided 360° immersion and enabled eye tracking for head movements and over-the-shoulder glances. Drivers were recruited based on urban cycling experience (inexperienced/experienced) and driving style (cautious/assertive).Results showed that in 47.8 % of intersection approaches, participants failed to adequately check for cyclists from behind. Driver characteristics did not consistently reveal traits associated with this neglect. Although cautious drivers with urban cycling experience made fewer mistakes, all groups were generally poor at checking for cyclists from behind. Post-drive questionnaire results on rule knowledge showed that, across participants, only half of the requirements to check for cyclists approaching from behind were indicated correctly.Drivers are more consistent in checking for cross-traffic, suggesting the neglect to check for cyclists is systemic rather than individual. The lack of awareness among drivers about their obligation to check for cyclists can be attributed to the less obvious nature of this traffic stream, as it comes from behind and lacks signs or warnings. Checking over the shoulder is physically more effortful, and cyclists may often pre-empt collisions, reinforcing drivers’ mental models to turn without checking. To improve safety, changes counteracting systemic biases against cyclists are needed.

Increased cycling, also in rural areas, is important for transitioning to a more sustainable transport system. Also, long combination vehicles (LCVs), in Sweden labelled high-capacity transport (HCT; up to 34.5 m, the previous limit was 25.25 m) can contribute to this goal. If granted access to a larger share of the road network, those trucks can be used more effectively. However, cycling and other active transport on those roads may be negatively impacted. To investigate direct and indirect effects on cyclists when LCVs are using the same road, a study was conducted in real traffic. Nineteen experienced road cyclists rode on a 5 km long rural road segment. Three trucks of different lengths were driven along the same route, instructed to overtake the cyclists where possible and with a full lane change. This generated 175 overtakes by the trucks and 607 overtakes by other traffic. The cyclists reported the overtakes with the trucks to feel safe and found the length of the truck not to be relevant if a full lane change was made while overtaking. The trucks needed more time to overtake than other traffic, and they also waited longer for an overtaking opportunity. In a car-following situation, the clearance of the following vehicles was influenced by the lead vehicle, making it especially important for heavy vehicles to give cyclists a wide berth. Pending further investigations, the conclusion is that for cyclists to feel safe, a full lane change when overtaking should be standard procedure not only for LCVs, but for motorised traffic in general.

Since December 2023, so-called High-Capacity Transport vehicles (up to 34.5 m length) are allowed on parts of the Swedish network of primarily divided roads. Investigations are ongoing under which premises longer HCT vehicles can be allowed on undivided rural roads, where cyclists and other active travellers may be present. On rural roads, overtaking manoeuvres are a frequently occurring encounter between cyclists and motorists. The fear related to dangerous overtakes is a major deterrent to rural cycling, and the aerodynamic load generated especially by large vehicles may pose a danger in that it could affect cyclist stability. To systematically investigate the effects of lateral distance, overtaking vehicle speed and truck length on cyclists stability and perception of discomfort, a controlled study was conducted in a laboratory setting. In a 700 m long tent, 23 experienced road cyclists rode on free rollers while being overtaken by a 16.5 m and a 32.5 m long truck combination at 50 and 80 km/h, with lateral distances of 1 m, 1.5 m and 2 m. Additionally, a reference overtake was run, reflecting a full lane change at reduced speed (16.5 m truck, 50 km/h, 3.5 m). Lateral distance had the largest impact on aerodynamic load and discomfort ratings, followed by speed. The length of the truck only had a minor effect. The cyclists’ lateral position on the rollers was not affected by any of the three factors, but increased slightly from before to during to after the overtaking manoeuvre, regardless of the condition. Based on these findings, a full lane change is recommended when overtaking cyclists. To which extent a speed adaptation is appropriate as compensatory measure needs to be investigated further.

AbstractCamera‐based Driver Monitoring Systems (DMS) have the potential to exploit eye tracking correlates of alcohol intoxication to detect drunk driving. This study investigates how glance, blink, saccade, and fixation metrics are affected by alcohol, and whether possible effects remain stable across three different camera setups, as well as when the driver is out‐of‐the‐loop during level 4 automated driving (Wizard‐of‐Oz setup). Thirty‐five participants drove on a test track first sober and then with increasing intoxication levels reaching a breath alcohol concentration (BrAC) of 1‰. Linear Mixed‐Effects Regression analyses showed that with increasing intoxication levels, eye blinks became longer and slower, glances and fixations became fewer and longer, and more attention was directed to the road area, at the expense of more peripheral areas. Fixation and blink metrics were more robust to changes in automation mode, whereas glance‐based metrics were highly context dependent. Not all effects of alcohol intoxication could be measured with all eye tracking setups, where one‐camera systems showed lower data availability and higher noise levels compared to a five‐camera system. This means that lab findings based on higher quality eye tracking data might not be directly applied to production settings because of hardware limitations.

Current guidelines for work zones do not consider the needs of cyclists and pedestrians enough, which leads to unpredictable situations and a resulting higher crash risk for these road user groups. With respect to motor vehicles, speed management with various interventions is an important and well-studied measure. Their design can be hazardous for cyclists, but a systematic investigation of speed reducing interventions that are applicable to cyclists is lacking. In a controlled setting, four different types of interventions were studied regarding their effect on cyclist speed, attention, and comfort at the first encounter with the intervention and when familiar with the setup. Thirty cyclists with a variety of bicycles first rode a baseline condition to establish their desired speed, then they encountered the interventions eight times in a row. During the first encounter their speed dropped but went back to baseline levels during the following trials, regardless of intervention type. The glance behaviour showed that cyclists' attention was focused much more on the interventions themselves than beyond, which can be problematic in unpredictable environments like work zones. Comfort ratings varied widely, with interventions causing vibrations being rated as least comfortable. To conclude, speed-reducing interventions for cyclists must be applied with care and their effect weighted against potential risks of causing crashes and distraction.

Cycling is good for health and the environment, and urban traffic planning is increasingly focused on making cycling easier and safer for everyone. Cycling in rural areas also has a high potential for increased cycling, but fundamental knowledge about rural road cycling is missing. This study aims to investigate the prevalence of rural cycling and the perceptions of cyclists and motorists on rural roads, especially in overtaking situations. Cross-sectional data from three surveys with 1899 respondents in total were used, whereof one survey provides results representative for Swedish adults in terms of age, gender, income, educational level and geographical regions. In total, 38% of the respondents use rural roads as cyclists or pedestrians, 10% never use rural roads and the remaining 52% use rural roads as motorists only. Out of the latter, 44% stated that they would like to cycle on rural roads, but do not do so for various reasons. The way overtaking manoeuvres are experienced differs between motorists with and without cycling experience. Qualitative analyses revealed which factors make cyclists uncomfortable during overtaking manoeuvres on rural roads. These should be considered when developing recommendations for appropriate overtaking manoeuvres. Examples of application are legislation, motorist information campaigns, driver coaching and future vehicle automation systems.

Eye tracking is a common tool to assess drivers’ attentional state, either in real-time with the goal to prevent incidents, or offline, to understand underlying processes. While seemingly objective, eye tracking data can be coded and interpreted in different ways, which can have substantial effects on the results. The objective of this paper is to highlight and discuss the possibilities and limitations of three different approaches to code glance data: the direction-based encoding, the target-based approach, and the purpose-based approach. The direction-based coding scheme describes glances relative to the direction of travel. The target-based approach classifies the glance targets into different categories. The purpose-based approach needs additional layers of information to deduce the reason for the glance. This information encompasses road layout, traffic rules, and the presence and relevance of other traffic. Data from a field study with 23 participants driving an instrumented vehicle on an urban route was used to illustrate differences between the three methods. The results showed that the coding approach clearly affected the interpretation of the measured glance data. A purely target-based approach is limited by its inability to account for spare visual capacity and that also the absence of a target constitutes valuable information, and a purely direction-based approach does not account for the need to scan areas located off forward. The purpose-based approach requires contextual information that can be cumbersome to integrate. Regardless of the approach used, additional layers of contextual information increase understanding and interpretability, potentially at the cost of increased complexity. The three approaches are suitable for different contexts and their feasibility also depends on the availability of additional data. A key message is that context awareness improves the accuracy of driver attention monitoring and inattention identification.

While the negative effects of alcohol on driving performance are undisputed, it is unclear how driver attention, eye movements and visual information sampling are affected by alcohol consumption. A simulator study with 35 participants was conducted to investigate whether and how a driver’s level of attention is related to self-paced non-driving related task (NDRT)-engagement and tactical aspects of undesirable driver behaviour under increasing levels of breath alcohol concentration (BrAC) up to 1.0 ‰. Increasing BrAC levels lead to more frequent speeding, short time headways and weaving, and higher NDRT engagement. Instantaneous distraction events become more frequent, with more and longer glances to the NDRT, and a general decline in visual attention to the forward roadway. With alcohol, the compensatory behaviour that is typically seen when drivers engage in NDRTs did not appear. These findings support the theory that alcohol reduces the ability to shift attention between multiple tasks. To conclude, the independent reduction in safety margins in combination with impaired attention and an increased willingness to engage in NDRTs is likely the reason behind increased crash risk when driving under the influence of alcohol.

This study aimed to explore how travelling in different group constellations (alone, with known or with unknown people) affects children's and adults' visual behaviour in traffic when cycling or walking. Additionally, mobile phone/earphone usage was considered, too. A follow-along study (n = 43) and an observation study (n = 898) were conducted to observe travellers in a natural setting. In the follow-along study, eye-tracking was used to investigate children's glances behaviour on their way to school and how well they manage to fulfil attentional requirements. The observational study focused on children's and adults' visual behaviour at several intersections. The main result of the study was that group membership appears to have a large influence on individuals' visual sampling strategy. In formal groups reliance on each other was found to be stronger than in informal groups. People with a natural responsibility in the group, such as parents or other adults, take a more active role in visual monitoring. Reliance on others is found to a greater extent among pedestrians than cyclists. Regarding communication devices, the use of earphones did not significantly affect glance behaviour towards relevant areas. In naturalistic situations, group constellation, age and phone/earphone usage are interlinked, which needs to be considered when studying these factors.

OBJECTIVE:The aim of this review is to identify how visual occlusion contributes to our understanding of attentional demand and spare visual capacity in driving and the strengths and limitations of the method.BACKGROUND:The occlusion technique was developed by John W. Senders to evaluate the attentional demand of driving. Despite its utility, it has been used infrequently in driver attention/inattention research.METHOD:Visual occlusion studies in driving published between 1967 and 2020 were reviewed. The focus was on original studies in which the forward visual field was intermittently occluded while the participant was driving.RESULTS:Occlusion studies have shown that attentional demand varies across situations and drivers and have indicated environmental, situational, and inter-individual factors behind the variability. The occlusion technique complements eye tracking in being able to indicate the temporal requirements for and redundancy in visual information sampling. The proper selection of occlusion settings depends on the target of the research.CONCLUSION:Although there are a number of occlusion studies looking at various aspects of attentional demand, we are still only beginning to understand how these demands vary, interact, and covary in naturalistic driving.APPLICATION:The findings of this review have methodological and theoretical implications for human factors research and for the development of distraction monitoring and in-vehicle system testing. Distraction detection algorithms and testing guidelines should consider the variability in drivers' situational and individual spare visual capacity.

Active travel is beneficial for individuals and society in many ways. As transportation habits are formed at a young age, active school transport should be promoted. However, young children are often portrayed as not being able to cope with the demands traffic imposes on them. Most studies tend to confirm the notion that older children perform better than younger children, however, they are usually conducted in controlled environments that are unfamiliar to the participants. Here, 28 participants in two age groups (6–12 and 13–18 years) cycled their usual way to school to guarantee familiarity with the environment. They wore eye trackers, and the surroundings were filmed by a camera on the handlebars and by another camera mounted on the bicycle of an experimenter, who followed the participant. For each trip, all attentional target areas were identified based on infrastructure layout, traffic rules and turning direction. It was coded whether the children monitored these areas. Additionally, glance targets and glance purpose were coded. More than 80 % of all target areas were monitored. Regardless of age, a higher number of simultaneous target areas increased the likelihood that some relevant target areas were missed. The glance distribution across different types of target areas did not vary between the age groups. An increase in the number of simultaneous target areas led to a decrease in spare visual capacity and an increase in glances dedicated to checking for traffic. Overall, children in both age groups were generally attentive in their familiar environment. Difficulties were associated with a higher number of simultaneous target areas. A more controlled setup is needed to identify potentially modifying factors, and a comparison with adults is needed to for a fair valuation of the children’s performance.

This paper presents initial work on a context-dependent driver distraction detection algorithm called AttenD2.0, which extends the original AttenD algorithm with elements from the Minimum Required Attention (MiRA) theory. Central to the original AttenD algorithm is a time buffer which keeps track of how often and for how long the driver looks away from the forward roadway. When the driver looks away the buffer is depleted and when looking back the buffer fills up. If the buffer runs empty the driver is classified as distracted. AttenD2.0 extends this concept by adding multiple buffers, thus integrating situation dependence and visual time-sharing behaviour in a transparent manner. Also, the increment and decrement of the buffers are now controlled by both static requirements (e.g. the presence of an on-ramp increases the need to monitor the sides and the mirrors) as well as dynamic requirements (e.g., reduced speed lowers the need to monitor the speedometer). The algorithm description is generic, but a real-time implementation with concrete values for different parameters is showcased in a driving simulator experiment with 16 bus drivers, where AttenD2.0 was used to ensure that drivers are attentive before taking back control after an automated bus stop docking and depot procedure. The scalability of AttenD2.0 relative to available data sources and the level of vehicle automation is demonstrated. Future work includes expanding the concept to real-world environments by automatically integrating situational information from the vehicles environmental sensing and from digital maps.

In darkness it is legally obligatory to light vehicles, both to enable their operators to see where they are travelling and to make the vehicle visible and recognisable to other road users. Legal requirements differ between vehicle types and, for bicycle lighting, also between countries. So far, in spite of some indications, there is no definite evidence of a relationship between crashes involving cyclists and darkness, nor on the presence of bicycle lighting and crash risk in darkness, possibly due to a lack of prevalence data. There are no standards for scientific or consumer testing of bicycle lights, and visibility-related results are inconclusive. Three test methods were employed to evaluate generic bicycle light features such as beam shape, brightness, steady versus flashing beam, and mounting position for their effects on seeing and being seen, while investigating which method was best suited for which type of evaluation. In static indoor laboratory testing, brightness was measured and beam shape documented photographically. In static outdoor testing, visibility from 300 m was evaluated, subjective ratings were collected, and beam shape documented. Three front-light beam types were then evaluated for their effect on gap acceptance in a dynamic setting in an urban environment, and subjective ratings were collected. All 18 tested lamps fulfilled the legal requirements, with a bright, steady front beam receiving the highest subjective ratings. Gap acceptance was influenced only by cyclist speed, but neither by beam type nor mounting position. To capture the effect of generic bicycle light features on perception, behaviour, and acceptance, one single method is not enough, and standardised laboratory tests should be combined with research-question–specific dynamic testing.

Cycling on the pavement is commonly seen in urban environments despite often being prohibited. This study explores this practice by analysing cycling on pavements in the wider socio-technical context in which it occurs. Using data from two field studies and one questionnaire study, as well as applying a Social Practice Theory (SPT) based analytical approach, the study explores the frequency of cycling on the pavement. The results show that riding on the pavement is common among cyclists. Three main configurations of meaning, material and competence constitutes this practice which is summarised as follows: avoiding the space of the car, increasing smoothness of the ride and unclear infrastructure design. Cycling on the pavement can be regarded as a way of managing safety and risk, seeking more efficient and comfortable paths of travel, as well as the outcome of perceiving the infrastructure as ambiguous. Overall, the study argues that cycling on the pavement is a consequence of skewed power relations between different modes of transport, as well as policies, urban planning and infrastructure not harmonising with demands for safe and smooth travel by cyclists.

Eye tracking (ET) has been used extensively in driver attention research. Amongst other findings, ET data have increased our knowledge about what drivers look at in different traffic environments and how they distribute their glances when interacting with non-driving related tasks. Eye tracking is also the go-to method when determining driver distraction via glance target classification. At the same time, eye trackers are limited in the sense that they can only objectively measure the gaze direction. To learn more about why drivers look where they do, what information they acquire foveally and peripherally, how the road environment and traffic situation affect their behavior, and how their own expertise influences their actions, it is necessary to go beyond counting the targets that the driver foveates. In this perspective paper, we suggest a glance analysis approach that classifies glances based on their purpose. The main idea is to consider not only the intention behind each glance, but to also account for what is relevant in the surrounding scene, regardless of whether the driver has looked there or not. In essence, the old approaches, unaware as they are of the larger context or motivation behind eye movements, have taken us as far as they can. We propose this more integrative approach to gain a better understanding of the complexity of drivers' informational needs and how they satisfy them in the moment.

Aim Road users, such as cyclists and car drivers, are constantly adapting to each other and to the road infrastructure. This study aimed to investigate what trade-offs can be observed when drivers and cyclists adapt to other road users and to the infrastructure. Methods A semi-controlled study was carried out in an urban traffic environment, where all participants travelled the same route twice, once as a cyclist and once as a car driver. The extended control model was used as an analytical framework to examine how people adapt depending on their main and current road-user role, experiencing different infrastructure and complexity. Results The results revealed possible trade-offs made while adapting, mainly in relation to rule-following. No differences in adaptive behaviour between people who mostly drive and people who mostly cycle were found. The current situational demands influence both the need to adapt and the adaptation carried out. A more complex traffic environment led to increased information intake, measured by glance behaviour.

With encounters between trucks and cyclists still being a major safety issue and physical as well as technological improvements far from ubiquitous implementation, training truck drivers in anticipatory driving to improve their interaction with cyclists may be a way forward. After a baseline drive in an urban environment, truck drivers inexperienced with urban driving received a dedicated training on anticipatory driving, followed by another drive along the same route several weeks later. The drivers were also interviewed about their opinion about the training. The drivers’ behaviour changed from before to after training, resulting in a better speed management in general, and a more intensive monitoring of the cyclists. There were also some improvements with respect to the placement in relation to the cyclist, but this effect was limited mainly because truck drivers performed well already before the training. The observed results correspond well to the opinions and feelings about the training that were reported by the drivers in the interview. Thus, driver training can possibly be one contributor to an increase in safety in urban areas.

The prevalence of mobile phone usage in traffic has been studied by road-side counting, naturalistic driving data, surveillance cameras, smartphone logging, and subjective estimates via surveys. Here, we describe a custom-made smartphone logging application along with suggestions on how future such applications should be designed. The developed application logs’ start and end times of all phone interactions (mobile phone applications, incoming/outgoing phone calls and text messages, audio output, and screen activations). In addition, all movements are automatically classified into transport, cycling, walking, running, or stationary. The capabilities of the approach are demonstrated in a pilot study with 143 participants. Examples of results that can be gained from smartphone logging include prevalence in different transportation modes (here found to be 12% while driving, 4% while cycling, and 7% while walking), which apps are being used (here found to be 19% navigation, 12% talking, 12% social media, and 10% games) and on which road types (rural, urban, highway etc.). Smartphone logging was found to be an insightful complement to the other methods for assessing phone use in traffic, especially since it allows the analyses of which apps are used and where they are used, split into transportation mode and road type, all at a relatively low cost.